Combustor floating collar assembly

ABSTRACT

A combustor floating collar assembly having a floating collar disposed about an opening in an outer surface of a combustor liner. The floating collar is displaceable relative to the outer surface. A retention plate is attached to the outer surface of the combustor liner and traps the floating collar between the outer surface and the retention plate. At least a portion of the retention plate engages the floating collar and biases it toward the outer surface.

TECHNICAL FIELD

The disclosure relates generally to gas turbine engine combustors and,more particularly, to a floating collar assembly for a combustor fuelnozzle or igniter.

BACKGROUND

Igniters of gas turbine engine combustors are typically retained on aboss of the gas generator case by being directly threaded into the bossor by being held in position with bolts. The igniters interface with thecombustion chamber through a floating collar that is retained by abracket. The bracket provides the collar with freedom of movement in theplane of its contact with the boss, and the collar is free to movenormal to the bracket boss.

During engine operation, the collars may be exposed to aerodynamic loadsgenerated by the upstream compressor which exert a force on the floatingcollar. When this force is greater than the inertial or gravitationalloads on the collar, the collar is displaced. The dynamic nature of suchaerodynamic loading, coupled with combustor dynamics, can create afretting problem due to the intermittent displacement/impact of thecollar against the igniter, or against the bracket or boss.

SUMMARY

There is provided a combustor floating collar assembly, comprising: afloating collar disposed about an opening in an outer surface of acombustor liner, the floating collar being displaceable relative to theouter surface; and a retention plate attached to the outer surface ofthe combustor liner, the retention plate trapping the floating collarbetween the outer surface and the retention plate, at least a portion ofthe retention plate engaging a portion of the floating collar andbiasing the floating collar toward the outer surface.

There is also provided a gas turbine engine combustor, comprising: anannular combustion chamber defined by a combustor liner, the combustorliner having a plurality of openings therein extending between an innersurface and an outer surface of the combustor liner; a plurality offloating collars each disposed about one of the openings in the outersurface of the combustor liner, each floating collar being displaceablerelative to the outer surface; and a plurality of retention platesattached to the outer surface, each retention plate trapping acorresponding one of the floating collars between the outer surface andthe retention plate, at least a portion of each retention plate engaginga portion of the floating collar and biasing the floating collar towardthe outer surface.

There is further provided a method for installing an annular floatingcollar about an opening in a liner of a gas turbine engine combustor,comprising: positioning the floating collar on an outer surface of theliner, the floating collar being displaceable with respect to the outersurface; attaching a retention plate to the outer surface to trap thefloating collar between the outer surface and the retention plate; andbiasing the floating collar toward the outer surface with at least aportion of the retention plate.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is now made to the accompanying figures in which:

FIG. 1 is a schematic cross-sectional view of a gas turbine engine;

FIG. 2 is a side view of a combustor of the gas turbine engine of FIG.1, the combustor having a floating collar assembly according to anembodiment of the present disclosure;

FIG. 3 is a perspective view of a floating collar assembly on thecombustor of FIG. 2, according to an embodiment of the presentdisclosure;

FIG. 4A is an enlarged, partially-sectioned perspective view of thefloating collar assembly of FIG. 3;

FIG. 4B is a side view of the enlarged, partially-sectioned view of thefloating collar assembly of FIG. 4A, shown without a floating collar;and

FIG. 4C is another, enlarged partial side view of the floating collarassembly of FIGS. 3-4B.

DETAILED DESCRIPTION

FIG. 1 illustrates a gas turbine engine 10 of a type preferably providedfor use in subsonic flight, generally comprising in serial flowcommunication a fan 12 through which ambient air is propelled, acompressor section 14 for pressurizing the air, a combustor 16 in whichthe compressed air is mixed with fuel and ignited for generating anannular stream of hot combustion gases, and a turbine section 18 forextracting energy from the combustion gases. The combustor 16 includes acombustion chamber 17 defined by a combustor liner 19 which contains andconveys the hot combustion gases. The combustor 16 is housed within agas generator case 3.

Referring to FIG. 2, the shape of the combustor 16 is typically definedby the combustor liner 19 which may include one or more relatively thinsheet metal walls supported within a plenum filled with compressed air.The compressed air typically enters the combustor 16 through variousopenings 15 in the combustor liner 19 and/or via fuel nozzles, to mixwith the fuel sprayed within the combustor 16. Fuel nozzles or ignitersare inserted into the combustor 16 through some of the openings 15.

Many of the openings 15 are circumscribed by bosses 13, which can beannular or another shape and protrude from an outer surface 9 of thecombustor liner 19 about the openings 15 and coaxial therewith. The“outer surface 9” of the combustor liner 19 is the surface of thecombustor liner 19 which does not face inwardly into the combustor 16toward the hot combustion gases. The bosses 13 facilitate attachment orinsertion of fuel nozzles or igniters into the combustor liner 19 andallow for the mounting of collars to improve sealing between thecombustor liner 19 and the gas generator case. The bosses 13 can beformed during the manufacturing of the combustor liner 19, or can beattached thereto. If attached, the bosses 13 are welded to the outersurface 9 of the combustor liner 19. Whether integral with, or attachedto, the combustor liner 19, the bosses 13 are fixedly attached to thecombustor liner 19 and are not displaced relative thereto.

Referring to FIGS. 2 and 3, a floating collar assembly 20 is mounted tothe outer surface 9 of the combustor liner 19 about one of the openings15. Each floating collar assembly 20, and in particular, its floatingcollar, helps to seal the fuel nozzles or igniters in the openings 15.The floating collar assemblies 20 also help to accommodate the relativemovement between the fuel nozzles or igniters and the combustor 16,which results from thermal expansion and contraction. The floatingcollar assemblies 20 can also be used to control the flow of air fromthe plenum or gas generator case into the combustion chamber enclosed bythe combustor liner 19 of the combustor 16.

FIG. 3 shows the floating collar assembly 20, according to an embodimentof the present disclosure. The floating collar assembly 20 (or simply“assembly 20”) is mounted to the outer surface 9 of the combustor liner19. More particularly, and as shown in this embodiment, the assembly 20is mounted to one of the bosses 13 of the outer surface 9. It will beappreciated that the assembly 20 may be mounted directly to the outersurface 9 about an opening therein.

The assembly 20 includes a floating collar 30, having an annular orother shape, which engages the boss 13 and can be displaced relativethereto. The assembly 20 also includes a retention plate 40 whichconfines the floating collar 30 to the outer surface 9 and biases thefloating collar 30 toward the outer surface 9. When a fuel nozzle origniter 7 is inserted into the floating collar 30, it is then radiallylocated through a small tolerance loose fit with the floating collar 30,allowing radial growth and in plane play from the loose fit.

Referring to FIGS. 4A to 4C, the annular floating collar 30 has acombustor-facing first surface 32 that engages the outer surface 9,which is represented in this embodiment by the boss 13, and anoutward-facing second surface 34. A central collar aperture 36 extendsthrough the floating collar 30 between the first and second surfaces32,34, and is generally co-axial with the opening in the combustorliner. The central collar aperture 36 is adapted for axial engagementwith the cylindrical body of the fuel nozzle or igniter, in order toeffectively seal the combustor liner from uncontrolled entry ofcompressed air from the plenum. More particularly, a pressuredifferential across the floating collar 30 seals the first surface 32 tothe boss 13. The first surface 32 is disposed on the boss 13 such thatthe floating collar 30 can be displaced relative to the boss 13, as willbe described in greater detail below. The displacement of the floatingcollar 30 may be caused, for example, by aerodynamic loads from thecompressor or from vibration of the whole assembly.

Conventional floating collars can fret at the contact points with thefuel nozzle or igniter, or at the contact point with the boss, becauseof the intermittent displacement or “chattering” caused by theaerodynamic or vibration loads encouraging the displacement of thefloating collar 30 against the fuel nozzle or igniter in a highlydynamic environment. The retention plate 40 disclosed herein helps toreduce such fretting by biasing the floating collar 30 toward the boss13 to frictionally reduce at least some of this chattering movement.

More particularly, the retention plate 40 is attached to the outersurface 9 and/or its boss 13 such that relative displacement iseliminated between the retention plate 40 and the boss 13. The retentionplate 40 can be welded to the boss 13 to form weld lines 42 between theretention plate 40 and the boss 13. The retention plate can also beattached to outer surface 9 using any other technique. When installed,the retention plate 40 overlies both the boss 13 and the floating collar30 such that at least some portion of the floating collar 30 ispositioned between the boss 13 and the retention plate 40. Thedimensional interference of the retention plate 40 with the floatingcollar 30 frictionally limits displacement of the floating collar 30relative to the boss 13, thereby confining the floating collar 30 to theboss 13. It can thus be appreciated that the retention plate 40“retains” the floating collar 30 in sealing engagement with the fuelnozzle or igniter, and traps the floating collar 30 between itself andthe outer surface 9.

Referring specifically to FIG. 4C, and in addition to this retainingfunctionality, the retention plate 40 also provides a “loading”functionality. More particularly, at least a portion of the retentionplate 40 engages at least a portion of the floating collar 30 and biasesit toward the boss 13 with a biasing force F. The engagement of theretention plate 40 with the floating collar 30 provides a compressiveload, acting substantially radially inward on the second surface 34 ofthe floating collar 30, which pushes the (inner) first surface 32 of thefloating collar 30 toward and/or against the boss 13. When the firstsurface 32 abuts against and engages the boss 13, friction between thetwo surfaces creates a shear force or restraint of the floating collar30 in a plane of the boss 13. The shear restraint in the plane of theboss 13 can be greater than the aerodynamic loads which impact thefloating collar 30.

The retention plate 40 of the assembly 20 disclosed herein thereforemaintains its “retention” functionality while also helping to reduce oreliminate the fretting associated with conventional floating collars.This may be achieved, for example, because the biasing engagement of theretention plate 40 limits the displacement of the floating collar 30relative to the boss 13. For example, the biasing force F applied by theretention plate 40 may allow the floating collar 30 to displace only ina plane that is parallel to the plane of the boss 13. The biasingengagement of the retention plate 40 may thus reduce or preventdisplacement of the floating collar 30 in a direction parallel to acenter axis of the opening in the combustor liner. In such instances,the retention plate 40 is used to radially (i.e. a direction along thecenter axis of the opening) secure the floating collar 30 to the boss13, while still permitting relative movement between the floating collar30 and the boss 13 only in the plane of the boss 13, or directly alongthe outer surface 9. Allowing the floating collar 30 to be displacedrelative to the boss 30 or outer surface 9 helps accommodate the radialgrowth of the components of the assembly 20, and the in-plane play fromthe loose fit between the fuel nozzle or igniter and the floating collar30.

Various embodiments of the retention plate 40 can achieve suchfunctionality, all of which are within the scope of the presentdisclosure. FIGS. 4A-4C show one such embodiment of the retention plate40. The retention plate 40 includes a substantially planar middleportion 44 extending between two attachment portions 46 which areattached to the outer surface 9 and which extend radially outwardly fromthe middle portion 44. The attachment portions 46 may be curved at theirends toward the outer surface 9. A free extremity 48 of each attachmentportion 46 is fixedly attached to the boss 13 or outer surface 9. In oneembodiment, each free extremity 48 can be welded to the boss 13 to formweld lines 42 between the retention plate 40 and the boss 13, or theouter surface 9 of the combustor liner. The distance between the freeextremities 48 in this embodiment is greater than a diameter of thefloating collar 30, such that the retention plate 40 overlies a greaterextent of the outer surface 9 than the floating collar 30.

The retention plate 40 also has one or more inner biasing portions 49 ofthe retention plate 40 which engage the floating collar 30, and whichextend radially inwardly from the middle portion 44. The inner biasingportion 49 can be curved, bent, or otherwise protrude toward the boss13. Such a curved inner biasing portion 49 provides a curved line ofcontact with the second (outer) surface 34 of the floating collar 30which helps to reduce stress concentrations. In the embodiment shown inFIGS. 4A-4C, the retention plate 40 can engage the floating collar 30via one or more dimples or depressions 49A in the retention plate 40.Each depression 49A extends from the planar portion 44 toward the boss13 and contacts the second surface 34 of the floating collar 30. Othershapes for the inner biasing portion 49 of the retention plate 40engaging the floating collar 30 are also possible, including “U”-shapeddepressions.

The depression or engagement can be formed during installation of theassembly 20. For example, while welding the free extremities 48 of theattachment portion 46 to the boss 13, it is possible to also manipulatethe retention plate 40 to engage the floating collar. The biasing loadcan be therefore be pre-loaded, and created by bending the retentionplate 40 so that it interferes with the floating collar 30 at assemblyof the retention plate 40 to the boss 13. In some instances, theretention plate 40 will be secured to the boss 13 before positioning thefloating collar 30 on the boss 13. This would allow the floating collar30 to be a replaceable item with no need to remanufacture the collarassembly 20.

Still referring to FIGS. 4A to 4C, there is also disclosed a method forinstalling the annular floating collar 30 about the opening in thecombustor liner. The method includes positioning the floating collar 30on the outer surface 9 such that the floating collar 30 is displaceablewith respect to the outer surface 9. The retention plate 40 is attachedto the outer surface 9 to trap the floating collar 30 between theretention plate 40 and the outer surface 9. The retention plate 40 ismanipulated to bias the floating collar 30 toward the boss 13. Thebiased floating collar 30 may be prevented from being displaced in adirection normal to the outer surface 9, and may be allowed to displacealong the outer surface 9.

In an embodiment, the method includes applying a heat treatment to thewelded or attached retention plate 40. This can permitcontrol/normalization of the load applied on the floating collar 30 bythe biasing retention plate 40.

There is also disclosed a method for dampening displacement of anannular floating collar 30 that is already installed. More particularly,the method helps to dampen or reduce unwanted radial displacement of thefloating collar 30 relative to the annular boss 13 in assemblies wherethe floating collar 30 is confined to the boss 13 with the retentionplate 40 disposed over the floating collar 30 and fixed to the boss 13.Such a method can be used to adapt an existing floating collar assemblyto reduce displacement of the floating collar, such as duringafter-market maintenance. The method includes biasing the floatingcollar 30, by bending or another mechanical manipulation of a portion ofthe retention plate 40, toward the boss 13 with at least a portion ofthe retention plate 40. Alternatively, an existing retention plate canbe replaced with a pre-formed retention plate 40 having a biasingelement 49 as described above.

In light of the preceding, it can thus be appreciated that a fuel nozzleor igniter can be inserted through the opening 15 and remove therefromwithout any part of the floating collar assembly 20 being disturbed orremoved from the combustor liner. This ability of the retention plate 40to retain itself and the floating collar 40 in place, even when the fuelnozzle or igniter is positioned within the opening 15 of the combustorliner 19, prevents these components repositioning themselves relative tothe retention plate 40 during installation. This can be problematicduring installation of a collar assembly. Such functionality alsoimproves maintenance of the features of the assembly 20 because completedisassembly of the assembly 20 and its components is not required.Furthermore, easier access can be provided to the internal components ofthe gas generator assembly, e.g. for boroscope inspection. Thesepossibilities can be achieved by enhancing the components of aconventional floating collar assembly, and does not require addingadditional parts.

In contrast to some conventional floating collar assemblies, theassembly 20 disclosed herein does not require other components (e.g. thefuel nozzle, the igniter, or features of these) to maintain the floatingcollar 30 in place, or to apply the biasing force F with the retentionplate 40. Instead, the assembly 20 disclosed herein presents aself-contained “one-piece” solution, wherein the retention plate 40 bothretains the floating collar in place, and applies compressive loadingthereto.

The above description is meant to be exemplary only, and one skilled inthe art will recognize that changes may be made to the embodimentsdescribed without departing from the scope of the invention disclosed.Still other modifications which fall within the scope of the presentinvention will be apparent to those skilled in the art, in light of areview of this disclosure, and such modifications are intended to fallwithin the appended claims.

1. A combustor floating collar assembly, comprising: a floating collardisposed about an opening in an outer surface of a combustor liner, thefloating collar being displaceable relative to the outer surface; and aretention plate attached to the outer surface of the combustor liner,the retention plate trapping the floating collar between the outersurface and the retention plate, at least a portion of the retentionplate engaging a portion of the floating collar and biasing the floatingcollar toward the outer surface.
 2. The floating collar assembly ofclaim 1, wherein the retention plate includes a substantially planarmiddle portion extending radially outwardly to an attachment portionbeing attached to the outer surface.
 3. The floating collar assembly ofclaim 2, wherein retention plate includes an inner biasing portionextending radially inwardly from the substantially planar middleportion, the inner biasing portion extending toward the outer surfaceand contacting the floating collar.
 4. The floating collar assembly ofclaim 3, wherein said inner biasing portion of the retention platecontacting the floating collar is curved toward the outer surface. 5.The floating collar assembly of claim 2, wherein the attachment portionis curved toward the outer surface.
 6. The floating collar assembly ofclaim 2, wherein the attachment portion of the retention plate isfixedly attached to the outer surface.
 7. The floating collar assemblyof claim 6, wherein the attachment portion of the retention plate iswelded to the outer surface.
 8. The floating collar assembly of claim 1,wherein the floating collar is positioned on an annular boss of theouter surface, the retention plate including a substantially planarmiddle portion extending radially outward to an attachment portion beingattached to the boss.
 9. The floating collar assembly of claim 1,wherein said portion of the retention plate which engages the portion ofthe floating collar prevents displacement of the floating collar in adirection normal to the outer surface.
 10. A gas turbine enginecombustor, comprising: an annular combustion chamber defined by acombustor liner, the combustor liner having a plurality of openingstherein extending between an inner surface and an outer surface of thecombustor liner; a plurality of floating collars each disposed about oneof the openings in the outer surface of the combustor liner, eachfloating collar being displaceable relative to the outer surface; and aplurality of retention plates attached to the outer surface, eachretention plate trapping a corresponding one of the floating collarsbetween the outer surface and the retention plate, at least a portion ofeach retention plate engaging a portion of the floating collar andbiasing the floating collar toward the outer surface.
 11. The combustorof claim 10, wherein each retention plate includes a substantiallyplanar portion middle extending radially outwardly to an attachmentportion being fixedly attached to the outer surface.
 12. The combustorof claim 11, wherein the retention plate includes an inner biasingportion extending radially inwardly from the substantially planar middleportion, the substantially planar middle portion and the inner biasingportion overlaying the floating collar, the inner biasing portionextending toward the outer surface and contacting the floating collar.13. The combustor of claim 12, wherein the inner biasing portion of theretention plate contacting the floating collar is curved toward theouter surface.
 14. The combustor of claim 10, wherein each floatingcollar is positioned on an annular boss of the outer surface, thecorresponding retention plate including a substantially planar middleportion extending radially outwardly to an attachment portion beingfixedly attached to the boss.
 15. The combustor of claim 10, furthercomprising at least one igniter or at least one fuel nozzle, said nozzleor fuel nozzle being inserted through a corresponding one of theopenings, and engaging a corresponding floating collar.
 16. A method forinstalling an annular floating collar about an opening in a liner of agas turbine engine combustor, comprising: positioning the floatingcollar on an outer surface of the liner, the floating collar beingdisplaceable with respect to the outer surface; attaching a retentionplate to the outer surface to trap the floating collar between the outersurface and the retention plate; and biasing the floating collar towardthe outer surface with at least a portion of the retention plate. 17.The method of claim 16, wherein biasing the floating collar toward theouter surface includes compressive loading the floating collar with saidportion of the retention plate.
 18. The method of claim 17, whereincompressive loading the floating collar includes increasing a shearrestraint of the floating collar in a plane of the outer surface. 19.The method of claim 16, wherein biasing the floating collar includeswelding the retention plate to the outer surface to engage the floatingcollar with said portion of the retention plate.
 20. The method of claim16, further comprising inserting a fuel nozzle or an igniter through theopening in the liner to engage the floating collar, and removing thefuel nozzle or the igniter from the opening while maintaining in placethe floating collar and retention plate.